The Logic of Life: A History of Heredity (1974) 10/12/03. Reviewed by Jon Turney Francois Jacob on the evolution of ideas about heredity.

Molecular genetics in the 1960s was an intensely involving affair. For the first time, it was possible to understand something of the molecular machines which read, write and edit the genetic code. This, it seemed, was the essence of biology.

One scientist in those remarkable creative times, the Parisian François Jacob, stood a little apart from the rest. He was as involved as any in the new experiments and theories – he shared a Nobel Prize with his Pasteur Institute colleague Jacques Monod for their great work on gene regulation. But he nevertheless saw the new views of the cell not as the ultimate truth, but as merely one stage in the unfolding of ideas about living systems.

This became apparent in 1970 when he published, not a popularisation of the latest hot stuff, but an unusually reflective history of ideas about heredity and reproduction. It was cool, beautifully written (to judge by the English translation of a few years later) and unfailingly interesting. The new understanding of cells as governed by a DNA programme was still the culmination of the story. But unlike most popular histories of science, there was no royal road to truth, but a succession of world-views, each of which prompted different questions, with new answers.

It is an intellectually demanding take on the history of ideas, but so clearly presented that you hardly notice. You see how understanding the begetting of like by like was first preoccupied with the surface shapes of organisms, the visible structure. Then, as successive layers of organisation were revealed, so the ideas changed, in ways shaped by the new things formerly unseen and the cultural preoccupations of the time. The ancient tangle of forms, signs and affinities yielded to fixed species. Then came the elements making up individual members of a species. Then cells, genes within cells, and finally the molecules making the genes. Each shift in focus was as much reinvention of the biological world as advance in understanding.

Thirty or more years on, this view seems all the more persuasive. The Human Genome Project traded to some extent on the idea that everything in biology would be explained by teasing out the DNA text in more detail. Now the text exists, there is a search for new ways of tracking what is going on inside cells and organisms. The genome will always be a touchstone, but understanding the complexities of signalling and regulation inside cells raises new questions, perhaps with new kinds of answers.

None of that would have surprised Jacob – he and Monod, after all, first understood the workings of the simplest feedback system for switching genes on and off in bacteria. But as he put it at the close of his fine book: "Today the world is messages, codes and information. Tomorrow what analysis will break down our objects and reconstitute them in a new space? What new Russian doll will emerge?" A rhetorical question? We'll see.

Book details

Publisher: Pantheon Books, New York (1974). Penguin (1989).